When "The Cardinal Sins" was originally published 30 years ago it was an overnight success story, selling over three million copies and spending 52 weeks on The New York Times bestseller list. It's not difficult to see why. This lusty epic, re-released this month in paperback, lifted the veil (so to speak) on the sex lives of two dashing Catholic priests and the women who love them. No wonder it flew off the shelves. Kevin and Patrick, both bosom buddies, enter the seminary together, but their divergent paths and characters eventually lead them toward wildly differing fates. Kevin, the unwavering one given to high-handed pronouncements on doctrines of the faith, is surprised to find himself in conflict with almost everyone he knows. In contrast the laid back Patrick rises like a helium filled balloon through the church hierarchy, giving in to every athletically wicked temptation along the way. But when all his fast living catches up with him he turns - wouldn't you know it - to dry old Kevin for help. Author Andrew M. Greeley, himself a priest, writes about how ambition and temptation can come into conflict with the spirit, but be warned. Not every reader will be rooting for a clean getaway. Forge, $14.95.